Experiments are proposed to look at three parameters: (1) The immunogenicity of purified polysaccharides derived from Streptococcus mutans particularly with respect to their induction of secretory antibodies; (2) The induction of secretory antibodies by various routes and with use of various antigens; and (3) The function of secretory antibody in protection against colonization by bacteria and also against dental caries. BIBLIOGRAPHIC REFERENCES: Genco, R. J., Emmings, F.G., Evans, R.T., and Apicella, M. Purification, characterization, and immunogenicity of cell-associated glucan from Streptococcus mutans. J. Dent. Res. 55: Spec. C, C115-C120, 1976. Evans, R. T., Genco, R. J., Emmings, F. G. and Linzer, R. Antibody in the prevention of adherence: measurement of antibody to purified carbohydrates of Streptococcus mutans with an enzyme linked immunosorbent assay. Microbiology Abstracts, Special Supplement 1: 375-386, 1976.